Hello, folks. I wonder if anyone can help with a query? I bought a second hand Sauer last year and after cleaning it and testing a few homeloads I noticed that quite a few of the cases were a bit sooty, as if some of the charge had been trying to escape back through the chamber? This only happened after the barrel,chamber,etc were thoroughly cleaned and I have noticed no other abnormalities or warnings. Is this anything to worry about?

Sealgair, welcome to AR. A little more info might be helpful, for example, are you saying that you fired the rifle previously (prior to cleaning) with the same loads and no soot was evident on the cases?
Also, how many rounds have you fired post cleaning and noticed the soot on the cases?

Sometimes, a round that is low on the power spectrum, can cause an insufficient seal in the chamber, and allow the necks of the cases to become sooty. If it is more than the necks and shoulder area of the cases, I would be a little more concerned....

I wonder if it is possible, that you just loosened a lot of 'grime' when cleaning your rig, and it is now leaving some left behind loose deposits on the cases--one of the reasons I wonder how many rounds you have experienced this on. I would probably lean towards this explanantion without some other info, and just try and clean the chamber area out until it is good and dry, and 'debris' free.

good luck!

Fish is right. What caliber and what was the load? How were the brass resized? Were the brass previously fired in this same rifle? You may want to compare the measurements on a sized case and a fired case to make sure you are not over working the brass. It sounds like low power loads to me but with more info we could make a better guess.

Is it a gas gun, like an AR or a bolt gun? If it's a gas gun, the soot is probably getting to where it's getting because the chamber is large around the neck to allow easy chambering and extraction. If it's a bolt gun, the answer is most likely the same to a degree. In the US, we have SAAMI. They set standards for dimensions and all that good stuff. The diameter of the chamber in the neck is probably not that close so as to allow ammo from many manufacturers to fit. If the gun was a full-on target rig, the chamber would have maybe .002 to .003 inches clearance. A SAAMI gun has about .007 inches clearance. Under the extreme pressure and velocity in the gas, it can force itself into the small clearance between neck and chamber, but most likely not past the shoulder datum where the case snugs into the neck. Is there any soot right on the sloping shoulder? Probably not. If there is, the case has the shoulder too far down. Is the bolt hard to close? It should be easy if it's too far down and damned near impossible if it's too far up. If it's just right, you'll feel that in your hands if you close the bolt on an empty chamber. It should feel just like that with every closing because there is a space between the bolt and the case when it's closed of maybe .005 to .006 inches. That is the headspace we all talk about so much. Load up a dummy (no powder or primer, drill holes in the case) that gives you the best feel on closing and keep it around for reference when you load new bullets so you can measure it and make your new ammo a spittin' image of the previous ammo. You'll always have a place to start when seating the new bullets...

I suspect it could be a light charge and/or lack of consistent start pressure. Unless you are seating the bullet out to the lands, the case needs to have a good grip on the bullet to allow the pressure curve to rise. I find the best way to ensure this is to use a LEE Factory Crimp die. A standard roll crimp should work too.

I have the same problem. I bought my rifle new, CZ 7x57 and from day one it leaves soot on the neck of fired cases. About 50% of the neck turns black on one side. At first I thought it was leftover oil in the chamber but I make sure it is thoroughly clean before I fire the rifle. I reload .375 only so cant say if it happens with reloads also. Remember too that this rifle was brand new when I bought it so maybe someone else can shed some more light on this subject?

Cheers, everybody. Doesnt sound like too much to worry about. I think it may be a combination of me scrubbing out the chamber and the headspace. It is a .243 and the loads used were not maximum loads, but werent far back from max, either. The brass was once fired factory stuff that I had fireformed then neck sized. I was just a wee bit concerned as I had bought the rifle second hand and hadnt seen anything like that before.

243win can leave some soot on the case neck. If it runs up the shoulder, i would guess your load is to light using a slow burning powder like IMR 4350 or 4831 burning rates, with light bullets. A starting load of IMR 4350 with a 68 gr bullet will not expand the neck till your near maximum. Plus IMR 4350 is not a good powder for light bullets, but perfect for 80 to 90+ gr bullets.

Some powders seem to produce more soot on cases than others.

Varget has produced more soot for me than any other rifle powder I've used.

quote:

Originally posted by LE270:
Some powders seem to produce more soot on cases than others..

Amen!! throw in 680, 2400 and a lot of the medium burning rate ball powders. roger

bartsche hit the nail on the head. Some powders simply burn much more dirty than others. Some leave white residue instead of black, and again others leave very little. Good shooting.

can also be a sign of low pressure

To me - soot on the outside of the fired case indicates (1)underpowered load or (2) slow burning powder.

I don't worry about it because I prefer slower powders.

I have encountered this on two different occasions in the past whilst working on load development:

1) Too low of a charge

2) Bullet sat too long

When the charge was increased and the OAL shortened, the sooting vanished in both instances.

Jonathan